Precision saws or scroll saws are utilized for cutting detailed fret work and other intricate patterns in wood, plaster, and other materials. The saws typically employ parallel arms which hold a fine thin blade between said arms, the arms moved in tandem so as to affect the cutting action of the blade. The parallel arms or beams are pivotally mounted on trunnions which in turn are journaled to bearings carried by the frame of the scroll saw. At the opposite end of the beams, an adjustable bolt and spring is provided so as to maintain the blade under tension. A motor or other drive system is connected to one of the beams so as to reciprocate the beams in an up and down fashion on their trunnions such that the saw blade reciprocates in a generally vertical blade plane relative to the work piece for cutting purposes. Such scroll saws may be utilized to make both straight line and curved cuts in rather intricate patterns and shapes in a variety of sheet like materials including wood, metal, plastic and the like. Generally the teeth of the blade are so shaped such that the blade cuts only on the down stroke.
It is well known to provide a work piece hold down which partially surrounds the blade having as a primary function the hold down of the work piece being cut on the table during the upward stroke of the moving blade. The work piece hold down also offers some protection for the fingers and hands of the operator during the cutting action.
Developments in material sciences have created work piece materials of various densities, sawability and the like, thus the desire to precision saw thicker work pieces. Generally, the work piece hold down scroll saw apparatus provides a restricted clearance between the maximum elevation of the hold down position and the saw table. For example, hold down apparatus is frequently mounted behind the saw blade with a mounting head which is attached to an angled support rod. The rod frequently is passed under the saw head in order to align the mounting means of the hold down member behind the saw blade. Such cumbersome mounting apparatus limits the maximum clearance that can be achieved between the hold down member and the saw table, i.e., limiting the maximum thickness of a work piece which can be detail sawed by the scroll saw.
Improved performance of process machinery which provides maximum capacity either in size and/or volume is a common incentive for improvement. In other words, the best way to improve production and flow or production capability is to use processing machinery which provides high compatibility and versatility. The selection of the right machine according to the material to be processed to perform specific processing has great importance with respect to the level of utilization of the apparatus. For example, when acrylic or wooden materials are shaped by means of a regular scroll sawing machine, if the material is changed, the blade or even the whole set of the machine members must be changed accordingly because of various speed, motor requirement and/or work piece thickness. To change heads in an apparatus is very time consuming and the alternative is a non-economical approach of preparing a complete series of scroll sawing machines for different work piece dimensions and materials.
Additionally, many scroll saws are designed such that the work table is pivotally moveable with respect to the frame so as to permit bevel cuts in the work piece by inclining the work table and the work piece supported thereby relative to the vertical plane of the blade. Such beveled sawing on a pivoted work table further reduces the potential thickness of the work piece to be accommodated. If the work piece is too thick causing the stock to contact the hold down arm or mounting member, the complete hold down assembly must be removed which also removes a degree of precision in working with the work piece. In another aspect, the removal of hold down assembly because of limited work piece thickness accommodation poses safety problems through the removal of the hold down guard fingers.
The present invention overcomes the deficiencies of the prior art by providing a work piece hold down apparatus which allows maximum clearance between the hold down apparatus and the saw table through an offset hold down mounting support rod which is clamped to the saw frame member. The apparatus allows for maximum elevation of the work piece hold down and guard fingers in relationship to the saw table thus providing functionality of the scroll saw for enhanced work piece thickness.